Copper is an essential trace element that plays a fundamental role in the biochemistry of aerobic organisms. The long-term objective of these studies is to elucidate the biological roles of copper in human nutrition. Copper has a critical role in early human development, as evidenced by patients with Menkes disease, a fatal neurodegenerative disorder of childhood resulting from loss of function of a copper transport P-type Atpase. Despite the considerable clinical and experimental data indicating a role for copper in early embryonic development, the mechanisms and timing of the critical events affected by copper remain poorly understood, as experimental systems to elucidate the role of specific nutrients in early embryonic development are limited. The studies in this proposal are intended to utilize the zebrafish, Danio rerio, as a model organism to elucidate the role of copper in early development and to define the cellular and molecular determinants critical to this process. The precise molecular phenotype of copper deficiency in the developing zebrafish will be determined following treatment of embryos with a small molecule that interferes with copper delivery to the developing blastoderm. Specific genes involved in copper homeostasis and function that are critical for prenatal development will be identified by cloning and characterizing the copper phenotype mutants pinky and calamity and by performing a forward genetic screen for novel genes involved in embryonic copper metabolism. Finally, information derived from these studies will be utilized to develop novel therapeutic approaches for patients with Menkes disease by developing a fish model of this disease and performing a high-throughput chemical genomic screen to identify small molecules that will rescue the phenotype of the affected mutants. Taken together, the results of these studies will permit new insights into the role of copper in prenatal development and may allow for the discovery of novel therapeutic approaches to the prevention and treatment of birth defects arising from impaired copper homeostasis. In terms of